Ladder web for venetian blinds



July 2l, 1931-. G' F FRENCH ET AL I 1,815,196

LADDER WEB FOR VENETIAN BLINDS Filed Aug. 25, 1950 A? I I I fh??? W 04 eAeA/'w21' hit/Z I I I j' @w 22%. z @Mw-Manly.;

Patented July 21, 1931 TES PATENr OFFICE.

LAIDDER WEB SFOR VENETIAN BLINDS Application led August 25, 1930, SerialNo. 477,764, and in Great Britain September 14, 1929.

5 of intermittent straps prevent end'wise movement-of the laths.

An objection to Venetian blinds is that if subject to a draught, saywhen hung at an open window, or outside a window, or if in positionsother than the vertical, say over a sloping skylight, the laths are aptto be displaced, and allow lightto pass between them, and are alsoliable to rattle.

To -overcome such drawback, it has already been proposed to provideladder webs with double or two-ply woven straps, the

laths passing between the plies, but such tapes have been expensive andslow to manufacture, and have presented diiiiculties in weaving owing toan increased number of shuttles being needed, necessitating speciallooins with complicated dobby or jacquard motions.

The object of this invention is to provide a ladder web with doublestraps which can be woven with the same number of shuttles as' theordinary single strap webs, and at.

practically the same rate of production, which can be manufactured ata'cost very 9 little, if anything at all, above the cost' of theordinary single straps tape, using virtually standard looms, and withlittle complication in the warp-shedding devices.

According to the invention the improved ladder web is characterized bydouble straps wherein the second or extra strap is Jformed from an eXtrawarp or warps left unwoven for a portion or portions of its length. Inthe preferred example there are a number of warps left entirely freefrom weft during the weaving of the straps. Ladder Webs according tothis invention may be woven on the same looms used for single strapwebs, i. e. having four tiers of shuttles.

In a modification the extra strap of one part-width web may, for aportion of its length, be supplied with weft from the shuttle used toweave the ordinary strap of the other part-width web and vice versa.

In a further modification, the two straps of each pair are suppliedalternately with a number o' picks of weft, and the crossings over fromone strap to the other subsequently severed or removed.

The eXtra or dummy straps thus formed, not having to bear the weight ofa lath, but merely to lie on the top of the' lath, are quite sulicientto prevent displacement of the lath.

The dummy straps may be direct-ly above the usual straps or to one sidethereof, or even on the other half or side of the body wbs, but clear ofthe woven straps on that si e.

The invention will be further described with reference to theaccompanying drawings, wherein z- Figs. 1 and 2 are edge and side viewsrespectively of a ladder web constructed according to one form of theinvention.

Fig. 3 is a part sectional perspective view of the web shown in Figs. land 2, illustratingY the use of the improved double straps.

Figs. .Lto 7 arediagrammatic views illusltrating methods of weaving theimproved web, hereinafter described.

Fig. 8 is a view corresponding to Fig. 2, but to a smaller scale, andillustrating a further form of the invention.

As shown in Figs. l to 6, the ladder web comprises two full-width wovenwebs A, B, and two part-width woven webs C, D, the latter being woveninto the former at regular intervals. The extra or dummy straps in thisform of the invention consist of warp threads only, without weft, seeFigs. l to 3, and may be obtained by introducing a number of extra warpthreads a, or by selecting some of the warps of the part-width webswhere they are not woven into the body webs. During the time that theordinary straps C and D are being woven, these selected Warp threads donot shed or-divide with the ordinary warps b and c but are held fixed sothat no weft is inserted between them, see Flgs. 4, 5 and 6. This canconveniently be ac complished by adding additional hooks o1 ]a cks onthe acquard or dobby (or by lntroducing a second jacquard or dobby) andaddltional heald shafts, for the extra warps. A tape thus produced has alength of unwoven or floating warpthreads a against each woven strap,thus .producing the .desired double strap. The laths of the blind liebetween the double straps as 4may be seen from Fig. 3.

In another form of the invention, the extra strap is obtained as in thepreviously described example, i. e. by means of extra warps a, orselected warps, but during the time that the usual strap C or D is beingwoven into the two body webs (a distance of about 1% to 13/8 for a strapof the average length of 21/2, and represented by the reference d inFig. 8), the shuttle for such strap, which A throughout that period isnot putting weft into the strap, although crossing the web at each pick,is employed to insert weft in the warps -a forming the opposite extrastrap, as represented by the reference e in Fig.`8, the extra warpsbeing separated b'y' th'e healds to receive the weft. The shuttle forthe strap C inserts weft threads in the dummy opposite the strap D, andvice versa. This is accomplished by shedding the selected warps by meansof extra heald shafts fitted for the purpose. The weft threads will beinserted in the dummy straps for a length equal to the length taken upby the binding of the straps in the body webs. The weft in the dummystraps will only connect in the middle of the strap warps a but willspread out to a certain extent over the length of such straps.

. In a further form of the invention and as illustrated in Fig. 7, thelath straps are woven two-fold or V shape, that is to say, the straps Cand a or D and a are supplied alternately with weft from the sameshuttle and the shedding is such that say 6/ 8 picks of weft are firstinserted in the top half, then a similar number in the bottom half, andsoon. The two halves are thus oined by a number of crossings of weft 7to each strap, which on beingcut will -produce two tapes. These may beslightly imperfect owino to their each having ing double' straps one ofwhich isformed by selecting and holdin out a number of warps from theother whilst the latter is being woven, as set forth. l

2. A ladder web for Venetian blinds, having double straps one of whichcomprises unwoven warp threads which have not been' shedded during theweaving of the other, as set forth.

3. A ladder web for Venetian blinds having two full-width webs and twopart-Width webs and having double straps according to claim 2,characterized in that the otherwise unwoven warp threads of onepart-width web are supplied with weft from the vshuttle which normallyweaves the straps of the other partwidth web, whilst the latter is beingwoven into the full-width webs, as set forth.

4. A ladder web for Venetian blinds, having double straps, each of whichis formed in portions of its length by unwoven warp threads which havenot been shedded during the weaving .of the opposite parts of the other,as set forth.

In testimony whereof we have signed our names to this specification.

GEORGE FREDERICK FRENCH. ROGER FRENCH.

only half the usual number of picks and those distributed in periodicpatches, but the tendency will be for the weft to distribute itself overthe whole length of strapwarp (especiallyif a coarse weft is used)producing light tapes.

Whilst preferring the arrangement of extra warps only or part extrawarps and part weft to form dummy straps, .a length or lengths of narrowbraid or tape or cords may be used as part of the warp.

'What we claim is 1. A ladder web for Venetian blinds, hav-

